This invention relates generally to an assembly for coupling together the ends of a pair of tubes, the assembly being particularly suitable for use in coupling tubes made of plastic material.
The assembly of the invention generally relates to the type of assembly having two flange bushings with a flange angle of approximately 90.degree., a sealing arrangement with centering means and a pair of identical, semicircular shells having U-shaped cross-sectional profiles each with a resilient pawl or latch.
Tube couplings similar to those of the present invention are known in the prior art, for example, from Swiss Pat. No. 429,331. These couplings generally consist of two flange bushings with cylindrical flanks and of two semicircular rings having a semitoroidal central part and a semitubular flange which are held together by means of conical rings. Although these devices may generally give good results, correct dimensioning may cause certain difficulties. In the case of inaccurate or coarse tolerances, considerable forces may be transmitted by means of the conical rings. Without snap or catch grooves, frictional coefficients which may vary widely may affect the safety of the wedging or engagement characteristics.
Another embodiment of a tube coupling known in the prior art is known from Swiss Pat. No. 538,626. In this prior art device, the end face of a flange has annular grooves which partially surround a sealing ring that is located therebetween, the grooves being arranged directly adjacent the interior wall of the tube wherein there is a small gap between the tube ends and wherein the rear sides of the flange are surrounded by a clamping ring. The tube connection is characterized in that the back sides of the flange and the appropriate contact surfaces of the clamping ring form an approximate right angle with the longitudinal axis of the tube. The clamping ring is elastic and it is held together with locking devices formed by means of recesses in the clamping ring. This type of construction gives rise to a limitation with regard to the selection of the type of sealing rings.
Also, exact adjustment of the dimensioning of the sealing ring is necessary. While for actual clamping of the clamping ring over the flange, a plastics material with a modulus of elasticity that is as high as possible would be desirable-especially since this type of tube coupling is provided for steel tubes--there is simultaneously involved the desirability of providing a plastics material with a low modulus of elasticity in order to enhance the release of the safety groove.
The present invention is directed towards providing a tube coupling of the type previously mentioned, particularly with reference to Swiss Pat. No. 538,626, which involves a structure enabling economical manufacturing thereof, which is well adapted to utilization with plastics materials, which exhibits space-saving characteristics and which provides a positive and safe locking function while being capable of being radially dismantled.
A further aim of the invention is the provision of a structure for a tube coupling involving self-centering characteristics whose function does not depend upon the tolerances involved and which may be installed and removed in the radial direction without axial displacement of the tubes.